/*
 * Copyright [2019] No Copyright is Claimed
 * This is an OpenSSL-compatible implementation of the RSA Data Security, Inc.
 * MD5 Message-Digest Algorithm (RFC 1321).
 *
 * Homepage:
 * http://openwall.info/wiki/people/solar/software/public-domain-source-code/md5
 *
 * Author:
 * Alexander Peslyak, better known as Solar Designer <solar at openwall.com>
 *
 * This software was written by Alexander Peslyak in 2001.  No copyright is
 * claimed, and the software is hereby placed in the public domain.
 * In case this attempt to disclaim copyright and place the software in the
 * public domain is deemed null and void, then the software is
 * Copyright (c) 2001 Alexander Peslyak and it is hereby released to the
 * general public under the following terms:
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted.
 *
 * There's ABSOLUTELY NO WARRANTY, express or implied.
 *
 * (This is a heavily cut-down "BSD license".)
 *
 * This differs from Colin Plumb's older public domain implementation in that
 * no exactly 32-bit integer data type is required (any 32-bit or wider
 * unsigned integer data type will do), there's no compile-time endianness
 * configuration, and the function prototypes match OpenSSL's.  No code from
 * Colin Plumb's implementation has been reused; this comment merely compares
 * the properties of the two independent implementations.
 *
 * The primary goals of this implementation are portability and ease of use.
 * It is meant to be fast, but not as fast as possible.  Some known
 * optimizations are not included to reduce source code size and avoid
 * compile-time configuration.
 */

#ifndef HAVE_OPENSSL

#include <string.h>
#include <stdio.h>

#include "md5.h"

/*
 * The basic MD5 functions.
 *
 * F and G are optimized compared to their RFC 1321 definitions for
 * architectures that lack an AND-NOT instruction, just like in Colin Plumb's
 * implementation.
 */
#define F(x, y, z)                      ((z) ^ ((x) & ((y) ^ (z))))
#define G(x, y, z)                      ((y) ^ ((z) & ((x) ^ (y))))
#define H(x, y, z)                      (((x) ^ (y)) ^ (z))
#define H2(x, y, z)                     ((x) ^ ((y) ^ (z)))
#define I(x, y, z)                      ((y) ^ ((x) | ~(z)))

/*
 * The MD5 transformation for all four rounds.
 */
#define STEP(f, a, b, c, d, x, t, s)                            \
  do {                                                          \
    (a) += f((b), (c), (d)) + (x) + (t);                        \
    (a) = (((a) << (s)) | (((a) & 0xffffffff) >> (32 - (s))));  \
    (a) += (b);                                                 \
  } while (0)

/*
 * SET reads 4 input bytes in little-endian byte order and stores them in a
 * properly aligned word in host byte order.
 *
 * The check for little-endian architectures that tolerate unaligned memory
 * accesses is just an optimization.  Nothing will break if it fails to detect
 * a suitable architecture.
 *
 * Unfortunately, this optimization may be a C strict aliasing rules violation
 * if the caller's data buffer has effective type that cannot be aliased by
 * MD5_u32plus.  In practice, this problem may occur if these MD5 routines are
 * inlined into a calling function, or with future and dangerously advanced
 * link-time optimizations.  For the time being, keeping these MD5 routines in
 * their own translation unit avoids the problem.
 */
#if defined(__i386__) || defined(__x86_64__) || defined(__vax__)
#define SET(n)                                                  \
  *(reinterpret_cast<const MD5_u32plus *>(&ptr[(n) * 4]))
#define GET(n)                                  \
  SET(n)
#else
#define SET(n) (ctx->block[(n)] =                       \
                (MD5_u32plus)ptr[(n) * 4] |             \
                ((MD5_u32plus)ptr[(n) * 4 + 1] << 8) |  \
                ((MD5_u32plus)ptr[(n) * 4 + 2] << 16) | \
                ((MD5_u32plus)ptr[(n) * 4 + 3] << 24))

#define GET(n)                                  \
  (ctx->block[(n)])
#endif

/*
 * This processes one or more 64-byte data blocks, but does NOT update the bit
 * counters.  There are no alignment requirements.
 */
static const void *body(MD5_CTX *ctx, const void *data, uint64_t size) {
  const unsigned char *ptr;
  MD5_u32plus a, b, c, d;
  MD5_u32plus saved_a, saved_b, saved_c, saved_d;

  ptr = (const unsigned char *)data;

  a = ctx->a;
  b = ctx->b;
  c = ctx->c;
  d = ctx->d;

  do {
    saved_a = a;
    saved_b = b;
    saved_c = c;
    saved_d = d;

    /* Round 1 */
    STEP(F, a, b, c, d, SET(0), 0xd76aa478, 7);
    STEP(F, d, a, b, c, SET(1), 0xe8c7b756, 12);
    STEP(F, c, d, a, b, SET(2), 0x242070db, 17);
    STEP(F, b, c, d, a, SET(3), 0xc1bdceee, 22);
    STEP(F, a, b, c, d, SET(4), 0xf57c0faf, 7);
    STEP(F, d, a, b, c, SET(5), 0x4787c62a, 12);
    STEP(F, c, d, a, b, SET(6), 0xa8304613, 17);
    STEP(F, b, c, d, a, SET(7), 0xfd469501, 22);
    STEP(F, a, b, c, d, SET(8), 0x698098d8, 7);
    STEP(F, d, a, b, c, SET(9), 0x8b44f7af, 12);
    STEP(F, c, d, a, b, SET(10), 0xffff5bb1, 17);
    STEP(F, b, c, d, a, SET(11), 0x895cd7be, 22);
    STEP(F, a, b, c, d, SET(12), 0x6b901122, 7);
    STEP(F, d, a, b, c, SET(13), 0xfd987193, 12);
    STEP(F, c, d, a, b, SET(14), 0xa679438e, 17);
    STEP(F, b, c, d, a, SET(15), 0x49b40821, 22);

    /* Round 2 */
    STEP(G, a, b, c, d, GET(1), 0xf61e2562, 5);
    STEP(G, d, a, b, c, GET(6), 0xc040b340, 9);
    STEP(G, c, d, a, b, GET(11), 0x265e5a51, 14);
    STEP(G, b, c, d, a, GET(0), 0xe9b6c7aa, 20);
    STEP(G, a, b, c, d, GET(5), 0xd62f105d, 5);
    STEP(G, d, a, b, c, GET(10), 0x02441453, 9);
    STEP(G, c, d, a, b, GET(15), 0xd8a1e681, 14);
    STEP(G, b, c, d, a, GET(4), 0xe7d3fbc8, 20);
    STEP(G, a, b, c, d, GET(9), 0x21e1cde6, 5);
    STEP(G, d, a, b, c, GET(14), 0xc33707d6, 9);
    STEP(G, c, d, a, b, GET(3), 0xf4d50d87, 14);
    STEP(G, b, c, d, a, GET(8), 0x455a14ed, 20);
    STEP(G, a, b, c, d, GET(13), 0xa9e3e905, 5);
    STEP(G, d, a, b, c, GET(2), 0xfcefa3f8, 9);
    STEP(G, c, d, a, b, GET(7), 0x676f02d9, 14);
    STEP(G, b, c, d, a, GET(12), 0x8d2a4c8a, 20);

    /* Round 3 */
    STEP(H, a, b, c, d, GET(5), 0xfffa3942, 4);
    STEP(H2, d, a, b, c, GET(8), 0x8771f681, 11);
    STEP(H, c, d, a, b, GET(11), 0x6d9d6122, 16);
    STEP(H2, b, c, d, a, GET(14), 0xfde5380c, 23);
    STEP(H, a, b, c, d, GET(1), 0xa4beea44, 4);
    STEP(H2, d, a, b, c, GET(4), 0x4bdecfa9, 11);
    STEP(H, c, d, a, b, GET(7), 0xf6bb4b60, 16);
    STEP(H2, b, c, d, a, GET(10), 0xbebfbc70, 23);
    STEP(H, a, b, c, d, GET(13), 0x289b7ec6, 4);
    STEP(H2, d, a, b, c, GET(0), 0xeaa127fa, 11);
    STEP(H, c, d, a, b, GET(3), 0xd4ef3085, 16);
    STEP(H2, b, c, d, a, GET(6), 0x04881d05, 23);
    STEP(H, a, b, c, d, GET(9), 0xd9d4d039, 4);
    STEP(H2, d, a, b, c, GET(12), 0xe6db99e5, 11);
    STEP(H, c, d, a, b, GET(15), 0x1fa27cf8, 16);
    STEP(H2, b, c, d, a, GET(2), 0xc4ac5665, 23);

    /* Round 4 */
    STEP(I, a, b, c, d, GET(0), 0xf4292244, 6);
    STEP(I, d, a, b, c, GET(7), 0x432aff97, 10);
    STEP(I, c, d, a, b, GET(14), 0xab9423a7, 15);
    STEP(I, b, c, d, a, GET(5), 0xfc93a039, 21);
    STEP(I, a, b, c, d, GET(12), 0x655b59c3, 6);
    STEP(I, d, a, b, c, GET(3), 0x8f0ccc92, 10);
    STEP(I, c, d, a, b, GET(10), 0xffeff47d, 15);
    STEP(I, b, c, d, a, GET(1), 0x85845dd1, 21);
    STEP(I, a, b, c, d, GET(8), 0x6fa87e4f, 6);
    STEP(I, d, a, b, c, GET(15), 0xfe2ce6e0, 10);
    STEP(I, c, d, a, b, GET(6), 0xa3014314, 15);
    STEP(I, b, c, d, a, GET(13), 0x4e0811a1, 21);
    STEP(I, a, b, c, d, GET(4), 0xf7537e82, 6);
    STEP(I, d, a, b, c, GET(11), 0xbd3af235, 10);
    STEP(I, c, d, a, b, GET(2), 0x2ad7d2bb, 15);
    STEP(I, b, c, d, a, GET(9), 0xeb86d391, 21);

    a += saved_a;
    b += saved_b;
    c += saved_c;
    d += saved_d;

    ptr += 64;
  } while (size -= 64);

  ctx->a = a;
  ctx->b = b;
  ctx->c = c;
  ctx->d = d;

  return ptr;
}

void MD5_Init(MD5_CTX *ctx) {
  ctx->a = 0x67452301;
  ctx->b = 0xefcdab89;
  ctx->c = 0x98badcfe;
  ctx->d = 0x10325476;

  ctx->lo = 0;
  ctx->hi = 0;
}

void MD5_Update(MD5_CTX *ctx, const void *data, uint64_t size) {
  MD5_u32plus saved_lo;
  uint64_t used, available;

  saved_lo = ctx->lo;
  if ((ctx->lo = (saved_lo + size) & 0x1fffffff) < saved_lo)
    ctx->hi++;
  ctx->hi += size >> 29;

  used = saved_lo & 0x3f;

  if (used) {
    available = 64 - used;

    if (size < available) {
      memcpy(&ctx->buffer[used], data, size);
      return;
    }

    memcpy(&ctx->buffer[used], data, available);
    data = (const unsigned char *)data + available;
    size -= available;
    body(ctx, ctx->buffer, 64);
  }

  if (size >= 64) {
    data = body(ctx, data, size & ~(uint64_t)0x3f);
    size &= 0x3f;
  }

  memcpy(ctx->buffer, data, size);
}

#define OUT(dst, src)                           \
  do {                                          \
    (dst)[0] = (unsigned char)(src);            \
    (dst)[1] = (unsigned char)((src) >> 8);     \
    (dst)[2] = (unsigned char)((src) >> 16);    \
    (dst)[3] = (unsigned char)((src) >> 24);    \
  } while (0)

void MD5_Final(unsigned char *result, MD5_CTX *ctx) {
  uint64_t used, available;

  used = ctx->lo & 0x3f;

  ctx->buffer[used++] = 0x80;

  available = 64 - used;

  if (available < 8) {
    memset(&ctx->buffer[used], 0, available);
    body(ctx, ctx->buffer, 64);
    used = 0;
    available = 64;
  }

  memset(&ctx->buffer[used], 0, available - 8);

  ctx->lo <<= 3;
  OUT(&ctx->buffer[56], ctx->lo);
  OUT(&ctx->buffer[60], ctx->hi);

  body(ctx, ctx->buffer, 64);

  OUT(&result[0], ctx->a);
  OUT(&result[4], ctx->b);
  OUT(&result[8], ctx->c);
  OUT(&result[12], ctx->d);

  memset(ctx, 0, sizeof(*ctx));
}

void MD5_print(char *str, size_t len, const unsigned char *result) {
  for (int i = 0; i < 16; ++i) {
    snprintf(&str[i * 2], len - i * 2,
             "%02x", static_cast<unsigned int>(result[i]));
  }
  str[len - 1] = 0;
}

#endif

#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>

#ifdef TEST_MAIN
int main(int argc, const char **argv) {
  int total_size;
  struct stat st;
  if (argc < 2) {
    printf("not enough arg\n");
    return -1;
  }
  int file_fd = open(argv[1], O_RDONLY);
  int err = stat(argv[1], &st);
  if (err != 0) {
    printf("canot stat\n");
    return -2;
  }
  total_size = st.st_size;

  lseek(file_fd, 0, SEEK_SET);
  int read_size = 0;
  char md5_read_buf[1024];
  MD5_result md5_result;
  MD5_result_str md5_result_str;
  MD5_CTX md5_ctx;

  MD5_Init(&md5_ctx);
  while (read_size < total_size) {
    size_t left = total_size - read_size;
    int to_be_read = left < sizeof(md5_read_buf) ? left : sizeof(md5_read_buf);
    int rd = read(file_fd, md5_read_buf, to_be_read);
    if (rd != to_be_read) {
      close(file_fd);
      printf("%d + %d vs %d %d\n", rd, read_size, to_be_read, total_size);
      return -3;
    }
    MD5_Update(&md5_ctx, md5_read_buf, to_be_read);
    read_size += rd;
  }
  MD5_Final(md5_result.result, &md5_ctx);
  MD5_print(md5_result_str.str, sizeof(md5_result_str.str), md5_result.result);
  printf("%s\n", md5_result_str.str);
  return 0;
}
#endif
